Networking Personal Computers with TCP/IP


	Networking Personal Computers with TCP/IP By Craig Hunt 1st Edition July 1995 1-56592-123-2, Order Number: 1232 408 pages, $32.95

Windows 95 PPP

Windows 95 includes Point-to-Point Protocol (PPP), which is a protocol that allows TCP/IP to run over a dial-up connection (e.g., a modem). The same installation and configuration steps are required for a PC running TCP/IP over PPP as are required for any TCP/IP system. You must:

install and configure the network hardware. For PPP the network hardware is usually a modem.
load and configure the network software.
configure any required applications.

On a Windows 95 system, PPP is installed and configured using either the Internet Setup Wizard or the Network applet. I prefer the sense of control that I get from running the Network applet, the New Connection applet and the Modem Wizard manually. Others prefer the Internet Setup Wizard because it does all of these things in one process.
Installing PPP with the Internet Setup Wizard

Start the Internet Setup Wizard exactly as described in the Installing Windows 95 TCP/IP section earlier in this chapter. The wizard begins by checking the network hardware. Some piece of hardware that is capable of transmitting data, either a network adapter or a modem, must be installed before TCP/IP is installed. When no network adapter is detected the wizard looks for a modem. If the modem is already configured, the wizard displays the How to Connect window shown in Figure 6-10. Otherwise, the Internet Setup Wizard displays the You Need a Modem window. If you see that window, make sure the modem is turned on and connected to a COM port, and then click Next. This causes the Modem Wizard to run, which displays the Install New Modem window. Click Next in this window to allow the Modem Wizard to automatically search the COM ports for the modem. This should work in most cases. However, if the wizard makes a mistake in detecting the modem, click Change in the Verify Modem window and select the correct modem from the list that is displayed. To prevent the wizard from automatically detecting the modem, for example when you have more than one modem attached to the PC, check the Don't detect my modem box in the Install New Modem window. This displays a modem list that allows you to manually install and configure the modem.

Figure 6-10: How to Connect

When the Modem Wizard is finished, the Internet Setup Wizard displays the How to Connect window shown in Figure 6-10. Select I already have an account with a different service provider to use your corporate PPP server. The Use the Microsoft Network selection is only used to connect a PC to the Internet and is primarily for home users.
After the wizard loads the necessary software, it prompts for the name of your Internet service provider. It doesn't really need to be the name of a service provider. Enter a descriptive name. The name is used to create a connection profile for this link. For example, my connection to O'Reilly is named ORA. You might use the name Main Office for the connection to the server at your central office.
You're then prompted for the phone number of the remote server, as shown in Figure 6-11. For a server that requires a special login, check Bring up a terminal window after dialing to manually login to the server. After testing the link, automate the login process by creating a login script as described in the Creating Login Scripts section later in this chapter.

Figure 6-11: The PPP Server's Phone Number

The wizard then prompts for the username and password used to login to the remote server. The username and password are requested irrespective of whether or not Bring up a terminal window after dialing was checked. The values entered here are used as the default username and password for this connection.
The remainder of the configuration is almost identical to the LAN configuration with two minor differences. When prompted for the IP address you are again given the option of manually assigning the address through the window or obtaining the address automatically from the server. This time, however, the automatically assigned address comes from the PPP server as part of the the PPP protocol. Unlike the LAN example, DHCP is not required. The second difference is that if the PC does not have a network adapter, you are not prompted for a default gateway because, if PPP is the only connection to the network, the server at the other end of the PPP link must be the default gateway. Continue through the wizard's other prompts answering them as before until you press the Finish button.

Figure 6-12: Dial-Up Networking

Test the new connection by opening the Dial-Up Networking folder in My Computer, which is an icon normally displayed at the top of the screen that provides a high-level view of the devices installed in the computer. The folder will contain an icon with the name you assigned to the PPP connection. (Figure 6-12 shows a sample Dial-Up Networking folder with a new connection called Main Office.) Double-click the icon to start the connection. The Connect To window, also shown in Figure 6-12, appears. Enter the username and password and click Connect. The modem should dial and connect to the remote server. If you requested the terminal window, it will open to allow you to finish the login process (see Figure 6-19). Enter the necessary login commands and click F7 Continue.
There should now be an active PPP connection. Test the connection using the PING command from the MS-DOS window. (See the Windows 95 Network Applications section for examples of the PING command and the MS-DOS command-line interface.) If errors are reported by PING, see Chapter 5 for advice on interpreting the error messages. Use the Network applet, described in the next section, to correct configuration problems.
This concludes our coverage of installing PPP with the Internet Setup Wizard. The next section describes how the Control Panel is used to install and configure PPP. If you used the wizard, you can skip ahead to Creating Login Scripts.
Installing PPP from the Control Panel

Begin by installing the Dial-Up Adapter. Run Network from the Control Panel and click the Add button. In the Select Network Component Type window, highlight Adapter and click Add. The Select Network Adapter window shown in Figure 6-13 appears.

Figure 6-13: Selecting the PPP Adapter

Highlight Microsoft in the Manufacturers subwindow and Dial-Up Adapter in the Network Adapters box. Click OK. The PPP device driver is then loaded from one of the Windows 95 diskettes. You may be warned that only one dial-up adapter is allowed. Ignore the warning. Only one dial-up adapter will be installed. Multiple PPP connections are handled by the new connection wizard, not by installing multiple dial-up adapters.
The system returns to the Network window, which shows that two new network components are installed. One of the new components is, of course, the dial-up adapter. The other is TCP/IP, which is automatically installed with the dial-up adapter.
Figure 6-14 shows the Network window after PPP has been added to a system that already has a LAN adapter. Notice that the TCP/IP associated with the dial-up adapter is clearly labeled as TCP/IP -> Dial-Up Adapter and not just TCP/IP as it would be on a system with only one adapter. The configuration being defined for PPP is separate from the configuration already defined for the Ethernet, which is very useful for laptops that are sometimes docked into a LAN and are at other times used on the road. We saw a similar approach used in Chapter 5 when we configured Chameleon's software, which allowed SLIP and PPP configurations to coexist with a system's Ethernet configuration.

Figure 6-14: PPP with Other Adapters

To configure PPP, highlight TCP/IP -> Dial-Up Adapter and click Properties. This displays a set of tabs used to define the IP address, subnet mask, and default gateway. Each interface has its own address, so the values entered here do not interfere with the values entered for the Ethernet interface.
One exception occurs when the system connects to a remote PPP server while still being connected to the Ethernet. In that case, it is possible to have two default routes (one from the Ethernet configuration and one from the PPP configuration) installed at the same time. Use the ROUTE command, which is covered in the Windows 95 Network Applications section of this chapter, to delete the Ethernet default route while testing the PPP connection. If PPP and Ethernet normally are used at the same time, use either an Ethernet default route or a PPP default route, but not both. See Chapter 2 for advice on selecting a default route.
Complete the basic PPP configuration by highlighting Dial-Up Adapter and clicking Properties. The window shown in Figure 6-15 appears. The window contains three tabs: Advanced, Bindings, and Driver Type.

Figure 6-15: PPP Adapter Configuration

The Advanced tab sets the following PPP properties:

Prioritize WAN for IP

Set the value of this property to Yes. Windows 95 relies on TCP/IP as its primary WAN protocol. Anyone using TCP/IP should leave this value set to Yes. Only use No if your primary WAN protocol is some other PPP-compatible protocol.

Record a log file

When set to Yes, it creates a log of the PPP connection process. The log is stored in C:\WINDOWS\PPPLOG.TXT. Use it for debugging problems that occur during the PPP protocol negotiations. Otherwise leave this value set to No.

Use IP header compression

Set this value to Yes if your remote server supports header compression. It increases performance. Only set the value to No if you are sure the remote system cannot operate with header compression.

Use IPX header compression

Ignore this parameter on a pure TCP/IP network. However, when using NetWare, set the value to Yes unless the remote server cannot support IPX header compression.

The Bindings tab associates transport protocols with the dial-up adapter. Make sure that TCP/IP is checked on this tab.
The Driver Type tab defines the type of driver used with the dial-up adapter. The system limits the driver selection based on the characteristics of the software installed earlier in the dial-up configuration. The tab may offer up to three choices:

Enhanced mode (32-bit and 16-bit) NDIS driver

This is the default, and it is the one you should probably use.

Real mode (16-bit) NDIS driver

Use this driver for compatibility with older TCP/IP software. A driver that was designed for Windows 3.1 may be a 16-bit NDIS1 driver.

Real mode (16-bit) ODI Driver

Use the ODI driver with NetWare client software that is not compatible with the NDIS driver.

The default values on all of the Dial-Up Adapter Properties tabs are probably just what you need. On most PPP clients, defining the TCP/IP configuration is enough. Usually you can ignore the other tabs. Once everything is set the way you want it, click OK and restart the system.
Making the PPP Connection

When the system reboots, it installs the Dial-Up Networking folder in My Computer.
Networking folder. The modem installation wizard runs if a modem has not yet been installed. (You can run the modem wizard any time you wish by opening Modems in the Control Panel.) The modem wizard automatically detects the type of modem connected to the system and configures it. If the wizard makes a mistake detecting the modem, click the Change button and select the correct modem from the modem list.

Figure 6-16: New Connection Wizard

After the modem driver is installed, the Dial-Up Networking folder opens to show the Make New Connection icon. Double-click the icon to run the new connection wizard. Figure 6-16 shows the opening window of this wizard. Enter a unique name to identify the connection--use something descriptive. Click Next and enter the phone number of the remote server in the appropriate boxes of the second window. That's all the information the wizard will request. You may, however, want to make sure that the modem is properly configured for this connection. To review or modify the modem configuration, click the Configure button. The modem configuration window shown in Figure 6-17 appears.

Figure 6-17: Modem Configuration

This configuration window contains three tabs: General, Connection, and Options. The General tab is used to set the baud rate and the COM port. The COM port should be correctly set by the modem wizard. The baud rate, however, may need to be adjusted to match the performance characteristics of the remote server to which you are connecting.
Use the Connection tab to set the data bits and parity, which should always be 8 and none respectively for a PPP or SLIP connection. Stop bits are usually 1. The Port Settings button allows you to modify the number of receive and transmit buffers. (Buffering only applies if the computer has a 16550 UART.) Set the buffers to the maximum for increased performance. If the PC has trouble connecting to the remote server with the high settings, slowly reduce the number of buffers until you find the right combination for maximum performance and reliability.

Figure 6-18: Advanced Connection Settings

The Advanced button on the Connection tab opens a window that contains several interesting fields. Figure 6-18 shows this window. Use it to set flow control, error control, compression and to enable logging. These settings are explained below:

If flow control is enabled, it should be set to Hardware (RTS/CTS). This is necessary for SLIP and works for PPP. SLIP and PPP also work with flow control disabled, though doing that pushes the responsibility for flow control up to the higher layer protocols. Never use the Software (XON/XOFF) setting with SLIP.
Error control is a safe bet for SLIP and PPP connections. However, don't require error control to connect. Error detection and recovery is handled by higher layer TCP/IP protocols even if the modems can't negotiate error control. But if you check Required to connect, the connection will be rejected if the modems cannot negotiate the same error control protocol.
Don't use modem data compression unless the serial port speed (the DTE speed) is greater than the modem speed (the DCE speed) at both ends. In other words, if you have a 9600 baud modem and the serial ports at each end are also set at 9600 baud, do not use data compression. It will actually slow things down. Use modem data compression when you have high-speed serial ports, e.g., 38,400 bps, and a low-speed link, e.g., 14,400 baud.
The cellular protocol setting is only used if the modem supports it and will be transmitting over a cellular phone. Cellular Digital Packet Data (CDPD) is an industry standard designed for transmitting TCP/IP over cellular phone networks. It requires special CDPD modems at both ends of the link. Only use this setting if your modem installation guide tells you to use it and you know that the remote system can handle it.
Modulation type is only used if your modem and the remote modem use non-standard modulation for transmitting data. For example if you bought a high-speed modem before 28.8 kbps modems were standardized, it may use a non-standard technique for transmitting high-speed data. Don't change the value in this field unless you know that you have to in order to communicate with the remote modem.
The string of modem initialization commands entered in the Extra Settings box are sent to the modem just before dialing. Use this box to override the default initialization values of the modem or the standard values set by the modem wizard. Check the modem's documentation for information on valid modem initialization commands.
The Record a log checkbox causes a log of modem activity to be written to the file MODEMLOG.TXT in the WINDOWS directory. Use this as a debugging aid when you suspect problems during the initial dial-up and connect sequence.

The most important item in the Options tab is labeled Connection control. It contains checkboxes that bring up a terminal window before or after the computer dials the remote system. Select the Bring up terminal window after dialing checkbox if the remote system requires a special login sequence. Use the terminal window, shown in Figure 6-19, to manually key in the special login instructions in order to debug the modem connection before attempting to debug the login script. Once you are sure that the modems are configured correctly and that the two systems can successfully exchange packets, develop a login script using the built-in Windows 95 script language as described in the next section.

Figure 6-19: PPP Connection Terminal Window

When everything is set up the way you want, exit the new connection wizard. It creates a new icon in the Dial-Up Networking folder and labels it with the name you provided. Double-click on this new icon to open the connection to the remote system. You're then prompted for a username and password. Enter them and click Connect. The computer will dial the remote system. If you have requested the connection terminal window, enter the login commands for the remote server in that window and click F7 Continue. Test the connection with the PING command in the MS-DOS window. If you have problems, see the Troubleshooting SLIP/PPP section in Chapter 5 for advice.

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